The tools conventionally available for the application of joint compound to a joint with an interior angle between two surfaces include an application hand with a pair of lateral portions which are at a fixed angle relative to one another with that angle matching the angle between the two surfaces. A container or compound tube of joint compound is typically attached to the head and a channel is provided from the opening of the container to an outlet relative to each of the lateral portions to apply the joint compound to both sides and the apex of an internal angle between two surfaces when a horizontally or vertically prior to applying paper tape by hand.
The surfaces to which the joint compound is applied are rarely finished with sufficient precision that the application of the joint compound requires no touchup work after application. Normally, at least some touchup work is required in order to ensure that all surfaces and sometimes the apex of the internal angle are properly covered with joint compound to allow the paper tape to adhere properly.
Existing applicator devices are available which apply the compound but only to walls at angles of either 90° to one another or 135° to one another. Splayed internal walls are quite often not at either of these angles and the angle between two walls may differ substantially.
It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.